Cooking utensil



v Patented Dec. 23, 1941 I UNITED STATESy PATENT OFFICE COOENSE FredParsons, Milwaukee, Wis. Application Novmbol 3, 1938, Serial N0. 238,503

(ci. 21e-ss) 6 Claims.

'I 'his invention relates to cooking devices, and more particularlywhere electrically heated.

A well known type oi cooking device, generally known to the trade aselectric roasters or electric cookers, provides a main food containerwhich is upwardly open, for insertion ci' food materials,

being closed during cooking operations by a re- :novabl'e cover. Theseroasters or cookers are used for baking, both for meats and pastries,and also for cooking oi.' vegetables, often simultane ously with meat.It is common practice to cook both roast meats and vegetables withlittle or no added water, and this type of cooking, as well as thebaking of cakes and pastry and various other operations requires thatthe bottom oi' the container should be evenly heated and should not beproved results, particularly one or more oi' the matters previouslyreferred to, and especially for substantially hotter than the air withinthe consides and bottom of the container, and particularly where thecontainer is relatively shallow or horizontally elongated as, forexample, in an oval form, or in the rectangular form shown herein.

In present types oi.' such devices, so far as I am aware, the necessaryheat conditions, such as described, are obtained only at the expense ofrelatively slow or inemcient heating or both. Slow heating provides timefor the heat to equalize in the container walls, and in the interior,but the delay is very objectionable during pre-heating oi' th'e utensilto an initial high temperature such as is required, for example, whereroasts must be initially evenly seared on all outer surfaces beforeproceeding with the roasting, to improve the iiavor and to retain thejuices.

It is a purpose of the invention to provide an improved electricallyheated cooking device in which the bottom wall of the food container andthe. air within the container can be heated to a relatively hightemperature which is substanl vice of a specific type, namely, a cookerof the type in which the food receiving opening is at the top of thecontainer, and in which the container is longer than it is wide, as forexample, rectangular or elliptical in horizontal outline, and oi'irnelectrically heated devices.

improve the construction and operation of cooking devices, especially inone or more of the matters previouslymentioned, and particularly forelectrically heated devices.

Th'e invention comprises the construction and combination of parts asherein illustrated, de-

scribed and claimed and such modication of the structure illustrated anddescribed as may be equivalent to the structures of the claims.

Throughout the specification the same reference characters have beenused for the same parts, and in the drawing:

AFigure 1 shows a cooking utensil incorporating the invention in one oiits forms and partly in vertical section taken approximately along theline I-I o! Fig. 2.

Figure 2 shows a top view of the same utensil. partly broken away andpartly in horizontal section 1taken approximately along the line 2-2 ofFis'.

Figures 3 and 4 are partial vertical sections of a modined form of theinvention.

I'he utensil of the form shown in Figs. 1, 2, and also in the modifiedforms shown in Figs. 3 and 4, has similiar food container, cover andframe parts, which will therefore be described in detail only for theutensil of Figs. 1, 2.

In the device of Figs. 1, 2 a main food container I0 is relativelyshallow and of horizontal form materially longer than its width. Thecontainer is upwardly open and has vertical side walls Illa andahorizontal bottom wall lub. The container side walls are ilangedoutwardly at the top as at lic in a form to provide an inner ledge toreceive and locate an upwardly removable cover Il, the iiange beingfurther outwardly extended as at Illd to rest on the top o1' side wallsIla of an upwardly open support or frame i2, which has a bottom wall12b. Both the side and bottom walls oi' the frame i2 are constructed ofspaced sheet material forming hollow wall spaces within which heatinsulating material oi' any suitable type, such as glass wool or .thelike, is packed as indicated at i3, I3. The top flange portions lild fitthe side walls |2a to space the container side walls lila atpredetermined dis- -tances inside the side walls I2a, the spacing beingsubstantially equal at all points around the lateral periphery of thecontainer.

tions Ind also support the container III for the bOOm wall ilib to bespaced at a predetermined The ilange por distance above the bottom wallIIb, the vertical spacing being substantially uniform over the area ofthe bottom wall Nb. The support or frame thus provides an upwardlyppenwell in which the spacing and positioning oi the container I asdescribed provides a relatively shallow bottom chamber I4 underneath thecontainer bottom wall Ib and above the bottom wallv I 2b of the outershell, and a vertical chamber I 5 of substantial width relative to itsheight and extended about the periphery of the container I0, the chamberI5 being substantially closed at the top by the flange Inc andcommunicating at the bottom into the bottom chamber Il at substantiallyall points about the periphery of the bottom chamber.

In the structure of Figs. 1, 2 the heating ele ment is a helicalresistance coil I1 supported inside the upwardly open well of thesupport or frame I 2 on insulators such as I8, which are carried on aframe I9 having a vertical member Isa xed with a horizontal bottommember lsb that is spaced above the bottom wallof the well by washers,such as 20, and retained by bolts or screws such as 2|. Element I'I ispreferably of such characteristics that when the operatingcurrent isconnected the coil quickly attains a high heat, suitable for radiationof considerable quantities of radiant heat energy.

The partition member Isa separates a portion of the lower chamber I linto a peripheral portion Ila and an inner portion Mb, the peripheralportion operating as a downward continuation of the vertical chamber Il,and a considerable portion of radiation from the heating element eitherdirectly radiated, or directly reiiected by the walls of chamber I5 orof its downward continuation Ila, is received by the container. sidewalls I0a.

'I'he partition member Isa operates at high heat which, thoughrelatively much lower than the heating element itself, is suiiicient fora certain amount of radiant heat to be directed from the inner surfaceof the partition member either directly to the bottom wall I0b or tothebottom that which rises to heat the side walls Illa.

wall by reflection from the upper surface of the bottom wall.I2b offrame I2.

To increase the thermal eiilciency of the device and particularly withrespect to obtainingv maximum eihciency in directing the radiant heatinwardly to heat the container walls, the interior surfaces of the sideand bottom walls I2a, I2b of the support or frame I2 are of a materialand iinish to operate as eiilcient reflectors. 'To effect *thisresultthe surfaces may be of chrome plate, for example, or any bright,preferably metallic,

surface which will withstand the heat. Such reector surfaces areparticularly desirable and effective for the reflection ci' radiantenergy within the vertical chamber IB and the supplelmental chamber Ila.The outer surface of the container I0, on the other hand, is of' amaterial and finish to relatively readily absorb radiant energy,particularly as to the exterior surface of the side walls thereof,whereby to be readily heated as stated.

In addition to the radiant heat directly or indirectly received by thecontainer side and bot- The inner bottom chamber Mb communicates withthe chambers I5, I 4a both through a top opening or channel Isc and abottom opening or channel led, both thevopenings extending substantiallyabout the periphery of chamber IIb. These openings provide for arestricted amount of interchange and circulation of air, limited topermit the air in the chambers I5, I la to circulate at a relativelyhigher `heat than the air in the inner lower chamber Mb, as long as theheating element is operating, but assisting equalization and levellingof heat in the chambers when the current is on.

The form and position of the partition members Isa, l Sb are such as tosubstantially prevent both direct radiation and direct conduction ofheat from the element II to the bottom wall IZb of the support or frame,and thereby to add materially to the thermal eiiiciency of the cookingutensil.

With the construction described the container I0 and its contents may bevery quickly raised to relatively very high heat, and during any periodof heat increase the temperature of the side walls IIIa is continuouslymaterially higher than the temperature of the bottom wall I0b, while theair within the container is of substantially the same temperature' asthe bottom wall, which is the desired heat ratia as previously pointedout. The relatively high temperature of the side walls, particularly theupper portions of the walls, is of no detriment and materially assistsin reducing the heating time required, especially .for pre-heating theutensil to relatively high temperatures.

When the current isfcut oil, after reaching av within the container, theequalizing being materially assisted by air movement between the severalchambers. It is to be noted, however, that,

even during the equalizing, the hottest air tends to rise to the upperlevel of chamber I5, thereby maintaining the upper portions of sidewalls Illa at diminishingly higher temperature than the bottom wall IIJbuntil equalizing is completed.

For convenience in pre-determining and maintaining desired temperaturesthe heating element is connected to a plug-in connector such as 35,Figs. 1, 2, serially through a temperature controlled switch device suchas 36. The connection of the element I1 of the structure of Figs. l, 2is illustrative. The temperature control device 36 may be of anysuitable well known construction such that at various temperatures ofthe container I0, as predetermined by the manual adjustment of anindicator means 36a operating through a shaft 36h, the circuit throughcoil I1 will be interrupted, but will be closed again as soon as thetemperature of container IIJ falls materially below that indicated byindicator 38a.

In such mode of operation of the cooking device a high `thermaleliciency is of special significance. The higher the efficiency thelonger the rupted and during which equalization of temperature in thewalls and contents of the container may proceed. Such control of thepresent device, by reason of the high thermal eiiiciency, results insubstantially .uniform temperatures being continuously maintainedthroughout the container, even at high heat.

'Ihe modied structure of Fig. 3 is the same in purpose and substantiallythe same in mode of operation and effect as the structure of Figs. l, 2.The support and container is the same as that of Figs. 1, 2 except thatthere is provided a depression or groove 40 formed in the lower supportwall |217, to efiect a peripheral chamber portion 40a operating in themanner of the pe ripheral chamber portion Ha of the other structure.vThe heating element l1 is supported at suitable intervals by insulatorsIl.

The modified structure of Fig. 4 is also the same in purpose andsubstantially the same in effect as the structure oi Figs. 1, 2. In thisinstance both the container and the support are substantially like thoseof the other structure. The heating element 50 is arranged in verticallyspaced peripheral loops, supported at suitable intervals by insulators5|. In this instance the i side wall Ina by reason of the form andposition oi' the heating element receives somewhat more of directradiation than in the other structures.

In both the modified structures o! Figs. 3, 4 the manner of heating thebottom plate differs somewhat from that o! the structures of Figs. 1,

2 but thev structures are such that the desired temperature ratios aremaintained together with quick heating oi the container, and the heat isY rapidly equalized when the current is off.

`What is claimed is:

1. A cooking utensil including an Aupwardly open food container havingabottom wall, and

a support therefor, together deilning an up wardly and laterally closedvertical chamber peripherally substantially surrounding said containerand a laterally and downwardly closed lowerchamber underneath saidbottom wall and communicating with said vertical chamber, and

electrically heated meansconcentrated and exposed at a lower level ofsaid chambers and of a form and position veifecting movement of airheated by said means substantially directly upwardly into said verticalchamber, said heated means being formed and extended to eiIect saidupward air movement substantially equally peripherally about saidcontainer, and said verticalchamber being oi' sufiicient lateral widthsub-v stantially throughout its lperipheral extension for simultaneousdownward movement of relatively width, said container having side wallsand horizontal bottom wall, a support for said container providing wallsforming together with the walls of the container an upwardly andlaterally closed vertical chamber peripherally substantially laterallysurounding the container and a downwardly and laterally closed lowerchamber underneath the container bottom wall and communicating with saidvertical chamber, and electrically heated means concentrated and exposedat a lower level of said chambers and of a form and position effectingmovement of air heated by said means substantially directly upwardlyinto said vertical chamber, said heated means being formed and extendedto effect said upward air movement substantially equally peripherallyabout said chamber irrespective of the non-circular and elongated formof said container, and said vertical chamber being of suiicient lateraldimension substantially throughout its peripheral extension forsimultaneous downward movement of relatively cool air, whereby to eilecta continuous and relatively rapid air circulation upwardly anddownwardly and substantially limited to within said vertical chamber andextending substantially uniformly peripherally about said container.

3. A cooking utensil as recited in claim 1 in which the inner and outerperipheral walls deiining said vertical chamber are respectivelyportions of said container and of said support, and the major part ofthe interior surface of said inner and outer peripheral walls arerespectively relatively absorbent and relatively highly reflective ofradiant heat energy received thereon from said heated means.

`4. A cooking utensil as recited in claim 2 in which the inner and outerperipheral walls deiining said vertical chamber are respectivelyportions of said container and of said support, and the major part ofthe interior surface of said inner and outer peripheral walls arerespectively relatively absorbent and relatively highly reflective ofradiant heat energy received thereon from said heated means.

5. A cooking utensil as recited in claim 2 including shielding meanswithin said lower chamber and interposed between said heated means andcontainer bottom wall for materially reducing direct radiation of heatenergy from said

